Heat exchanger and an air conditioner

ABSTRACT

According to one embodiment, a heat exchanger includes a pipe through which a fluid flows, and a supply device that supplies the fluid to the pipe. The pipe includes a flexible part deformed by flowing of the fluid, and a constricted part located at a downstream side of the flexible part along a flow direction of the fluid.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-207308, filed on Oct. 21, 2016; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a heat exchanger and an air conditioner.

BACKGROUND

As to a liquid and a gas (in a piping) having high temperature and high pressure by a compressor, they radiate a heat to an outside by a condenser. After that, the liquid and the gas become low temperature and low pressure via an expansion valve, and absorbs a heat from the outside. By performing above functions, heat exchange is repeated. In this heat exchanger, flow of a mixed phase flow refrigerant is unequal. As a result, an efficiency of heat exchange drops, which is a problem.

In order to improve the efficiency of heat exchange, thinning a thermal boundary layer of a heat exchange device to perform heat exchange is well known. For example, by attaching a shaker to a frame body which supports a fin and a heat transfer pipe, and by vibrating the fin and the heat transfer, the thermal boundary layer (having a heat adjacent to the fin) can be broken. In this case, the shaker and a controller which vibrates the shaker are necessary to be newly installed. As a result, component of the apparatus becomes complicated, and newly-installation of the shaker and the controller leads to cost-up, which are problems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one example of a heat exchanger according to the first embodiment.

FIG. 2 is a schematic diagram of one example of surface shape of a flexible part according to the first embodiment.

FIG. 3 is a schematic diagram of one example of a heat exchanger according to the second embodiment.

FIG. 4 is a schematic diagram of one example of a heat exchanger according to the third embodiment.

FIG. 5 is a schematic diagram of one example of an air conditioner according to the fourth embodiment.

DETAILED DESCRIPTION

According to one embodiment, a heat exchanger includes a pips through which a fluid flows, and a supply device that supplies the fluid to the pipe. The pipe includes a flexible part deformed by flowing of the fluid, and a constricted part located at a downstream side of the flexible part along a flow direction of the fluid.

Hereinafter, a heat exchanger and an air conditioner according to embodiments are described below with reference to drawings. Having the same reference numeral means the same component. Incidentally, the drawings are schematic or conceptual, a relationship between the thickness and width of each part, the dimensional ratio between parts, etc. are not necessarily the same as actual ones. Furthermore, even the same part may be depicted in the different dimensions or dimensional ratio among the drawings.

The First Embodiment

FIG. 1 is a schematic diagram of one example of a heat exchanger 1 according to the first embodiment.

As shown in FIG. 1, the heat exchanger 1 equips a heat transfer pipe 4 in which a fluid circulates, and a supply device to supply the fluid to the heat transfer part 4. Here, the supply device is a compressor 5 and an expansion valve 6. By the heat transfer pipe 4 to flow the fluid from the expansion valve 6 to the compressor 5 via an evaporator, and by the heat transfer pipe 4 to flow the fluid from the compressor 5 to the expansion valve 6 via a condenser 3, the fluid is circulated. In FIG. 1, a part of the heat transfer pipe 4, i.e., the part located in the evaporator 2 and the condenser 3, is shown as a heat transfer pipe 8.

In the heat transfer 1 of the first embodiment, heat exchange of the fluid is effectively performed by self-oscillation of a part of the heat transfer 1.

The fluid includes a liquid, a gas, or both thereof. Preferably, the fluid is water, air, or refrigerant such as fluorine compound, ammonia, hydrocarbon, carbon dioxide. Furthermore, the fluid includes another gas, oil, and so on.

The evaporator 2 is connected to the heat transfer pipe 4. By flowing the fluid (having low temperature and low pressure) into the evaporator 2 via the expansion valve 6, the fluid absorbs a heat from an outside air, and cools the outside air.

The evaporator 2 equips a plurality of tabular fins 7 aligned nearly in parallel and the heat transfer pipe 8 placed on the fins 7. The fins 7 and the heat transfer pipe 8 are located in contact with each other. The fins 7 are respectively located with a predetermined space therebetween, and a gas flows in the space. Respective shapes of the fins 7 are not limited to tabular shape. They may be a plurality of columnar fins 7 extended from a side face of the heat transfer pipe 8. Only if the heat transfer pipe 8 has a component of which area contacting the outside air increases, any component be applied. As a material of the fins 7, in general, aluminum, aluminum alloy, hydrophilic coat or corrosion resistance coat spread thereon, are used. The heat transfer pipe 8 is bent as S-shape, and located in contact with the fins 7. A condition that the fins 7 contacts the heat transfer pipe 8 includes the case that the heat transfer pipe 8 penetrates the fins 7.

As shown in FIG. 1, the heat transfer pipe 8 of the evaporator 2 equips a hollow flexible part 8 a and a hollow constricted part 8 b at the downstream side of the flexible part 8 a along the flow direction of the fluid. The heat transfer pipe 8 equips a plurality of pairs of the flexible part 8 a and the constricted part 8 b, and a heat, transfer pipe 8 c between the flexible part 8 a and the constricted part 8 b. The flexible part 8 a is formed by an expandable and shrinkable elastic organ. The elastic organ is a material such as a rubber. By applying a stress to the external form, the elastic organ is deformed (The flexible part is also called “a deformable part”). The constricted part 8 b is a part having an inner diameter smaller than that of the flexible part 8 a and narrower toward the flexible part 8 a. In detail, at a connection part between the constricted part 8 b and the heat transfer pipe 8 c, the constricted part 8 b has the same inner diameter as the heat transfer pipe 8 c. However, the inner diameter is gradually smaller from the heat transfer pipe 8 c to the flexible part 8 a. The constricted part 8 b may be formed by the same material as the flexible part 8 a, or the same material as the heat transfer pipe 8 c. The heat transfer pipe 8 c is a pipe-like tube, and a material (such as aluminum or copper) having high thermal conductivity is used. The heat transfer pipe 8 c and the constricted part 8 b are connected with an adhesive and so on. Furthermore, if the constricted part 8 b is installed to the heat transfer pipe 8 c, the flexible part 8 a and the constricted part 8 b are connected with an adhesive and so on. If the flexible part 8 a can be sufficiently adhered to the constricted part 8 b or the heat transfer pipe 8 c to prevent leakage of the fluid, any adhesive may be used. The inner diameter of the constricted part 8 b is preferably smaller than the inner diameter of the heat transfer pipe 8 c. However, the respective inner diameters thereof are not limited to this relationship. In above explanation, the inner diameter of the constricted part 8 b is gradually smaller toward the flexible part 8 a. However, the inner diameter is not limited to this shape, and may be constant.

Next, while the fluid is flown in the heat transfer pipe 8 of the evaporator 2, a function occurred at the heat transfer pipe 8 is explained.

First, the fluid (flown in the heat transfer pipe 8) passes the heat transfer pipe 8 c, and flows into the flexible part 8 a. Next, the fluid flows into the constricted part 8 b. The inner diameter of the constricted part 8 b at the side of the flexible part 8 a is smaller than the inner diameter of the heat transfer pipe 8 c. Accordingly, the fluid flown into the constricted part 8 b is stagnant, and turbulence occurs. By pressure change due to the turbulence, a wall of inner tube of the flexible part 8 a (formed by a rubber and so on) is vibrated. As a result, the flexible part 8 a starts self-oscillation. The fluid (passed from the constricted part 8 b) passes the heat transfer pipe 8 c neighborly positioned at the downstream side, and flows into the flexible part 8 a. As mentioned-above, a plurality of pairs of the flexible part 8 a and the constricted part 8 b exists. Accordingly, vibration (oscillation) occurs at each flexible part 8 a in the heat transfer pipe 8. In general, the fluid includes two-phase flow of a liquid and a gas. When the fluid flows into the constricted part 8 b, due to two-phase flow, the fluid makes the flexible part 8 a vibrate. Furthermore, by vibration of the flexible part 8 a, fluids of two-phase flow are mixed.

By this vibration of the flexible part 8 a, a contact area between the flexible part 8 a and the outside air is increased, and a thermal boundary layer as a resistance for heat exchange is thinned. As a result, heat exchange with the outside air is effectively performed. Furthermore, the fluid flow in the heat transfer pips by the constricted part 8 b is diffused by the turbulence. As a result, the fluid effectively contacts an inner wall of the flexible part 8 a, and heat exchange therebetween is quickened.

The condenser 3 is connected to the heat transfer pipe 4. The fluid (having high temperature and high pressure by the compressor 5) flows into the condenser 3. Accordingly, the fluid radiates a heat to the outside air, and the outside air is warmed.

As shown in FIG. 1, the condenser 3 equips a plurality of tabular fins 7 aligned nearly in parallel and the heat transfer pipe 8 placed on the fins 7. The fins 7 and the heat transfer pipe 8 are located in contact with each other. The fins 7 are respectively located with a predetermined space therebetween, and a gas flows in the space. In the same way as the evaporator 2, the heat transfer pipe 8 may penetrate into the fins 7. Components of the heat transfer pipe 8 and the fins 7 are same as those of the evaporator 2. The heat transfer pipe 8 equips a hollow flexible part 8 a and a hollow constricted part 8 b at the downstream side of the flexible part 8 a along the flow direction of the fluid. The heat transfer pipe 8 equips a plurality of pairs of the flexible part 8 a and the constricted part 8 b, and a heat transfer pipe 8 c between the flexible part 8 a and the constricted part 8 b. By this component of the heat transfer pipe 8, when the fluid flows into the heat transfer pipe 8, turbulence occurs at a part adjacent to the constricted part 8 b, and the flexible part 8 a starts self-oscillation.

The heat transfer pipe 4 connects the evaporator 2, the compressor 5, the condenser 3 and the expansive valve 6 in loops. The fluid flows inside of the heat transfer pipe 4, and the fluid flows into the heat transfer pipe 8 of the evaporator 2 and the condenser 3. As a result, the fluid circulates in the heat exchanger 1. As shown in FIG. 1, the fluid passes the heat transfer pipe 4 and the heat transfer pipe 8, and flows in clockwise rotation (CCW). The heat transfer pipe 4 is connected to the heat transfer pipe 8 c of the evaporator 2 and the condenser 3. The heat transfer pipe 4 is formed by a pipe-like tube. A material of the heat transfer pipe 4 is preferably same as that of the heat transfer pipe 8 c.

The compressor 5 converts an energy occurred by reciprocating motion (such as piston) to an energy included in the fluid. The compressor 5 makes the fluid have high temperature and high pressure. For example, the compressor 5 may be pomp, accumulator, and so on.

The expansion valve 6 is a valve to drop the pressure of the fluid. By reducing the pressure of the liquefied fluid having high temperature and high pressure, the fluid becomes in condition easy to be evaporated. The compressor 5 and the expansion valve 6 are connected to the heat transfer pipe 4 respectively. The compressor 5 and the expansion valve 6 supply the fluid to the heat transfer pipe 4, the evaporator 2 and the condenser 3. Accordingly, the compressor 5 and the expansion valve 6 are called as “a supply device”.

In above explanation, the fluid flows in clockwise rotation. However, the flows may flow in anticlockwise rotation (CCAW). If the fluid flows in anticlockwise rotation, respective functions of the evaporator 2 and the condenser 3 are reverse.

Next, components of the flexible part 8 a, the constricted part 8 b and the heat transfer pipe 8 c (of the heat transfer pipe 8) is explained in detail.

As mentioned-above, by the fluid flowing into the heat transfer pipe 8, the flexible part 8 a is self-oscillating. A surface of an outer shape of the flexible part 8 a functions as a heat transfer face. Accordingly, the outer shape of the flexible part 8 a is preferably a shape having a larger surface area. As the outer shape of the flexible part 8 a of the first embodiment, a diameter around the center of the flexible part 8 a is the largest, and the diameter is gradually smaller toward the constricted part 8 b and the heat transfer pipe 8 a, i.e., an ellipsoid shape. Furthermore, in order to raise the efficiency of heat exchange, a plurality of projections may be set up on the surface.

FIG. 2 is one example of the surface shape of the flexible part 8 a. As shown in FIG. 2, on the surface of the outer shape of the flexible part 8 a, a plurality of columnar or prism-shaped projections, a plurality of conical or pyramid-like shape projections, or a plurality of hemisphere-like projections, may be set up. Furthermore, by roughening the surface of the flexible part 8 a, the surface area may be increased.

A thermal boundary layer between the flexible part 8 a and the fluid becomes thin by self-oscillation of the flexible part 8 a. Here, the thermal boundary layer is a region where temperature of the fluid changes suddenly. For example, if the difference in temperature between a solid body and the fluid exists, the contact region thereof is called as “thermal boundary layer”. When velocity of the boundary layer is quicker, the thermal boundary layer becomes thinner. When viscosity of the fluid is higher, the thermal boundary layer becomes thicker. When the flexible part 8 a is vibrated, the thermal boundary layer becomes thinner, and heat exchange with the fluid becomes remarkable. Accordingly, by Young's modulus, a weight and a shape of the flexible part 8 a, a diameter and a passage resistance of the constricted part 8 b, and a pressure of the fluid flowing, a natural frequency of the flexible part 8 as and the pressure of the fluid flowing had better foe adjusted. For example, if the natural frequency of the flexible part 8 a is desired to be heightened, a material having high rigidity is preferably used. If the natural frequency of the flexible part 8 a is desired to be lowered, a material having low rigidity is preferably used.

In the heat exchanger 1 of the first embodiment, by installing the flexible part 8 a and the constricted part 8 b to the heat transfer pipe 8, the flexible part 8 a performs self-oscillation. As a result, efficiency of heat exchange between the fluid (flowing in the flexible part 8 a) and the outside air can be improved.

Furthermore, in the heat exchanger 1 of the first embodiment, a shaker and a vibration controller to vibrate the heat transfer pipe 8 and the fin 7 need not be installed to the outside. Accordingly, system component having low-cost and space-saving can be realized.

In above explanation, the heat transfer pipe 8 equips a plurality of flexible parts 8 a and a plurality of constricted parts 8 b. However, the number of the flexible parts 8 a and the number of the constricted parts 8 b are not limited to plural number. Only one pair of the flexible part 8 a and the constricted part 8 b may be used. In this case, efficiency of heat exchange between the fluid (flowing in the flexible part 8 a) and the outside air can be improved.

Furthermore, by setting up projections on the surface of the flexible part 8 a, a contact area between the flexible part 8 a and the outside air can be increased, and efficiency of heat exchange can be improved.

Furthermore, by installing the constricted part 8 b at the downstream side of the flexible part 8 a, the fluid (flowing into the constricted part 8 b) is diffused due to the turbulence. As a result, the fluid effectively contacts an inner wall of the flexible part 8 a , and efficiency of heat exchange can be improved.

The Second Embodiment

FIG. 3 is a schematic diagram of one example of the heat exchanger 1 according to the second embodiment.

As shown in FIG. 3, the heat exchanger 1 equips vibration generators 9 installed to the heat transfer pipe 4 at the upstream side of the evaporator 2 and the condenser 3 respectively. Other components thereof are same as the heat exchanger of the first embodiment.

Specifically, the vibration generator 9 is installed at a position between the compressor 5 and the condenser 3, and a position between the expansion valve 6 and the evaporator 2, respectively.

The vibration generator 9 flows out the fluid with a pulsation. The pulsation means that a flow of the fluid has a cyclic motion so that the flow pulsates, which is different from a steady flow. After flowing into the heat transfer pipe 8, the fluid having the pulsation flows inside the flexible part 8 a. The flexible part 8 a starts vibrating at the same cycle as that of the fluid flown from the vibration generator 9. In this case, the fluid having the pulsation desirably pulsates at the same frequency as the natural frequency of the flexible part 8 a. As a result, the amplitude increases by resonance of the flexible part 8 a, arid efficiency of heat exchange between the fluid and the outside air can be more improved.

For example, the vibration generator 9 equips a rotary valve, and generates a pulsation to the fluid by rotation of the rotary valve. A cycle of the fluid flow from the vibration generator 9 can be suitably adjusted by a pressure of the fluid flown from the compressor 5 and the expansion valve 6, a shape of the flexible part 8 a, and an inner diameter of the constricted part 8 b.

Furthermore, the vibration generator 9 may have not only a function to flow out the fluid cyclically but also a function to mix the fluid. In general,

the fluid includes two-phase flow of a liquid and a gas. By mixing the fluid, characteristic of two-phase flow becomes remarkable, and efficiency of heat exchange can be improved. As a mechanism for mixing, for example, by installing fans to a motor and by rotating the fans., the fluid may be mixed. As mentioned above, when the fluid having two-phase flows into constricted part 8 b, the fluid makes the flexible part 8 a vibrate. Furthermore, by vibration of the flexible part 8 a, the fluid having two-phase flow is mixed.

In the heat exchanger 1 of the second embodiment, by installing the vibration generator 9, the flexible part 8 a can be vibrated based on flowing of the fluid into the flexible part 8 a. Furthermore, by flowing into the fluid having vibration nearly equal to the natural frequency of the flexible part 8 a, the flexible part 8 a can be resonated. As a result, by thinning the thermal boundary layer between the fluid and the outside air, efficiency of heat exchange can be raised.

The Third Embodiment

FIG. 4 is a schematic diagram of one example of the heat exchanger 1 according to the third embodiment.

As shown in FIG. 4, the heat exchanger 1 equips a valve 10 capable of changing a diameter of a constricted part 8 b to flow the fluid, and a valve controller (not shown in FIG. 4) to control driving of the valve 10. Other components thereof are same as those of the heat exchanger of the first and second embodiments.

The valve 10 is installed to the downstream side of the flexible part 8 a and can change a diameter of the constricted part where the fluid flows. Namely, an opening part of the valve 10 is the constricted part. The opening part means a part where the valve is opened and a part where the fluid flows. The valve 10 is connected to the valve controller, and an opening of the valve 10 is controlled according to an instruction from the valve controller. When the valve 10 is completely closed, a sectional area of the inside of the heat transfer pipe 8 c is regarded as 0%. When the valve 10 is completely opened, the sectional area of the inside of the heat transfer pipe 8 c is regarded as 100%. Here, an operating ratio of the valve 10 is controlled with a range “0˜100%”. The valve 10 and the flexible part 8 a, and the valve 10 and the heat transfer pipe 8 c, are respectively adhered by an adhesive and so on. For example, the valve 10 is an electromagnetic valve, a magnetic valve, or a proportional control valve.

The valve 10 is installed to each of a plurality of flexible parts 8 a (positioned at the heat transfer pipe 8) at the downstream aide along a flow direction of the fluid. The opening ratio of each of the plurality of valves 10 can be changed independently.

Furthermore, by installing a pressure sensor at the upstream side of the flexible part 8 a and the downstream side of the valve 10 along the flow direction of the fluid, the opening ratio of the valve 10 may be adjusted based on the pressure data.

Furthermore, by imaging a vibration of the flexible part 8 a with a camera, a deformation amount of the flexible part 8 a is measured based on the image. Thus, by estimating a flow amount and a pressure of the fluid without a pressure sensor and a flow sensor, a flow of the fluid may be controlled.

As the camera, an optical camera, a high speed camera, a PSD (position Sensitive Detector) camera, a CCD (Charge Coupled Devices) camera, and so on, are used.

Furthermore, by attaching a strain sensor to the flexible part 8 a, a strain amount of the flexible sensor 8 a is measured. Thus, by estimating a flow amount or a pressure of the fluid, flow of the fluid may be controlled. As the strain sensor, a strain gage using a piezoelectric element or a sensor using a semiconductor element may be used.

In the heat exchanger 1 of the third embodiment, by installing the valve 10 to the downstream side of the flexible part 8 a, a constriction ratio (opening ratio) of the heat transfer pipe 8 can be freely changed. Furthermore, the opening ratio of the valve 10 can be adjusted based on vibration status of the flexible part 8 a. For example, even if an abnormal vibration occurs at the flexible part 8 a due to convection of the fluid, by opening the valve 10, the abnormal vibration can be avoided.

The Fourth Embodiment

FIG. 5 is a schematic diagram of one example of an air conditioner 11 according to the fourth embodiment.

As shown in FIG. 5, the air conditioner 11 equips a four-way valve 12 to switch heating and cooling, a compressor 5 having a heat storage 13, an indoor equipment 17, and an outdoor equipment 18. The air conditioner 11 includes the heat exchanger 1 according to the first, second, third embodiments.

The indoor equipment 17 prepares a fan (not shown in FIG. 5) to radiate air around the evaporator 2 to the indoor.

The outdoor equipment 18 prepares a fan (not shown in FIG. 5) to radiate air around the condenser 3 to the outdoor.

The four-way valve 12 is located at the heat transfer pipe 4 between the compressor 5 and the evaporator 2, and between the compressor 5 and the condenser 3 of the heat transfer 1. The four-way valve 12 switches a circulation direction of the fluid compressed by the compressor 5. Based on this circulation of the fluid, heating and cooling of the air conditioner 11 is switched. The heat storage 13 is installed at a circumference part of the compressor 5. A controller 16 is connected to the compressor 5, the four-way valve 12, the indoor equipment 15 and the outdoor equipment 18. The controller 16 controls driving thereof.

By switching the circulation direction of the fluid, the four-way valve 12 switches heating and cooling of the air conditioner 11. Based on the circulation direction of the fluid, .respective functions of the evaporator 2 and the condenser 3 of the heat exchanger 1 are switched. Namely, above-mentioned location of the evaporator 2 and the condenser 3 corresponds to the case that the fluid circulates in clockwise rotation (CCW), and the air conditioner 11 performs circulation of cooling. The fluid (having high temperature and high pressure by the compressor 5) flows into the condenser 3, and performs heat exchange with air around the condenser 3. In this case, by driving the motor of the fan, the outdoor equipment 18 radiates air having temperature risen to the outside. After that, the fluid becomes low temperature and low pressure via the expansion valve 6, and flows into evaporator 2. The fluid performs heat exchange with air around the evaporator 2. In this case, by driving the motor of the fan, the indoor equipment 17 radiates cooled air to the indoor.

When the circulation direction of the fluid is switched by the four-way valve 12, and when the fluid circulates in anticlockwise rotation (CCAW), the air conditioner 11 performs circulation of heating. Here, the evaporator 2 in the indoor equipment 17 functions as the condenser, and the condenser 3 in the outdoor equipment 18 functions as the evaporator.

If the air conditioner 11 functions as any of heating and cooling, the four-way valve 12 can be omitted.

The heat storage 13 stores heat of the compressor 5. For example, if heating operation of the air conditioner 11 is stopped based on a user's external instruction or an operation program, the compressor 5 stops heat generation, and a temperature of the compressor 5 surrounded by the heat storage 13 falls due to difference between the temperature and the outside air temperature. Accordingly, by radiating heat from the heat storage 13 to the compressor 5, temperature fall of the compressor 5 is suppressed. As a result, a rise performance for the air conditioner 11 to start heating is improved. The heat storage 13 includes a heat storage material. As the heat storage material, for example, a material including a compound having latent heat storage performance such as sodium sulfate hydrate, sodium acetate hydrate, paraffin, can be used. The heat storage 13 is a component used for heating in the air conditioner 11. If the air conditioner 11 does not have a function to heat, the heat storage 13 is not necessary.

The respective fans of the indoor equipment 17 and the outdoor equipment 18 equip a blade to send air and a motor to rotationally drive the blade. A shape of the blade may be propeller or roller. A quality of material of the blade may be plastic or metallic.

The controller 16 controls the number of rotation of the compressor 5, switching of the four-way valve, the number of rotation of the motor of the fan in the indoor equipment 17 and the outdoor equipment 18. For example, the controller 16 is formed by a computation device including an electronic circuit, an operation device to set an operation condition of the air conditioner 11, and a memory to store an operation history and the operation condition of the air conditioner 11. A method for controlling at least one of software and hardware is included in control of the air conditioner 11.

In the air conditioner of the fourth embodiment, by including the heat exchanger of the first, second and third embodiments, efficiency of heat exchange with the outside air is raised, and performance for beating and cooling can be improved.

Furthermore, a shaker to improve the efficiency of heat exchange need not be installed to the evaporator 2 and the condenser 3. As a result, the indoor equipment 17 and the outdoor equipment 18 can be compact.

In above explanation, the heat exchange 1 of the first, second and third embodiments includes the fin 7. However, the fin 7 is not necessary component. In the heat exchange 1, the heat transfer pipe 8 equips the flexible part 8 a and the constricted part 8 b. The flexible part 8 a performs self-oscillation while the fluid is flowing therein. Accordingly, even if the fin 7 is not equipped, the efficiency of heat exchange with the outside air can be improved.

While certain embodiments have been described, these embodiments have been presented by way of examples only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

What is claimed is:
 1. A heat exchanger comprising: a pipe through which a fluid flows; and a supply device that supplies the fluid to the pipe, the pipe includes a flexible part deformed by flowing of the fluid, and a constricted part located at a downstream side of the flexible part along a flow direction of the fluid.
 2. The heat exchanger according to claim 1, wherein the flexible part vibrates by being expanded and shrunk due to the flowing of the fluid.
 3. The heat exchanger according to claim 1, further comprising: a valve capable of changing an inner diameter of the constricted part; and a valve controller that controls driving of the valve.
 4. The heat exchanger according to claim 1, wherein the inner diameter of the constricted part is smaller than an inner diameter of the flexible part.
 5. The heat exchanger according to claim 1, wherein the flexible part is formed of an expandable and shrinkable elastic material.
 6. The heat exchanger according to claim 1, further comprising: a plurality of fins aligned in contact with the pipe.
 7. The heat exchanger according to claim 1, wherein the pipe includes a first flexible part deformed by the flowing of the fluid, a first constricted part located at the downstream side of the first flexible part along the flow direction, a second flexible part deformed by the flowing of the fluid and located at the downstream side of the first constricted pert along the flow direction, and a second constricted part located at the downstream side of the second flexible part along the flow direction.
 8. The heat exchanger according to claim 1, further comprising: a vibration generator installed to the pipe at an upstream side of the flexible part along the flow direction, that occurs a vibration to the fluid supplied from the supply device.
 9. The heat exchanger according to claim 1, wherein the supply device is a compressor that flows out the fluid having high pressure or an expansion valve that flows out the fluid having low pressure.
 10. An air conditioner comprising: the heat exchanger of claim 1; and at least one of a fan and a controller.
 11. The air conditioner according to claim 10, further comprising: a four-way valve that changes the flow direction of the fluid. 